Implement P0426: Constexpr for std::char_traits

llvm-svn: 291741

1 files changed, 16 insertions, 0 deletions

diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
index ba58684b8e2..71ab24898d6 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
@@ -12,10 +12,22 @@
 // template<> struct char_traits<char>
 
 // static int compare(const char_type* s1, const char_type* s2, size_t n);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<char>::compare("123", "223", 3) < 0
+        && std::char_traits<char>::compare("223", "123", 3) > 0
+        && std::char_traits<char>::compare("123", "123", 3) == 0;
+}
+#endif
+
 int main()
 {
     assert(std::char_traits<char>::compare("", "", 0) == 0);
@@ -38,4 +50,8 @@ int main()
     assert(std::char_traits<char>::compare("223", "123", 3) > 0);
     assert(std::char_traits<char>::compare("133", "123", 3) > 0);
     assert(std::char_traits<char>::compare("124", "123", 3) > 0);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }